I think the foam I used is doing its job. My understanding is that you're suppose to stuff the cabinet to the point where only low bass is coming out of the port. I've experimented with padding on zero to five sides of the cabinet and the three-sided padding that I have now seem best. With no padding, both bass and midrange comes out of the port, while five-sided padding reduces too much of the bass.

Maybe my cabinet's over-dampened?

gar.